Drowning Treatment & Management

The most critical role in management is prompt correction of hypoxemia and acidosis. The degree of hypoxemia is often underrecognized. Patients should receive 100% oxygen and should be monitored closely via pulse oximetry, blood gas analysis, or both. Consider intubation and positive end-expiratory pressure (PEEP) with mechanical ventilation in any patient with poor respiratory effort, altered sensorium, severe hypoxemia, severe acidosis, or significant respiratory distress.

Ventricular dysrhythmias (typically, ventricular tachycardia or ventricular fibrillation), bradycardia, and asystole may occur as a result of acidosis and hypoxemia rather than electrolyte imbalance.

Ascertaining whether the drowning occurred in warm or cold water is essential. This depends on the temperature of the water, not of the patient. Maintaining mild hypothermia (core temperature of 32-34ºC) may be indicated for 12-24 hours in patients who remain comatose after a drowning episode. ^{[54, 78, 83]}

Seizures should be appropriately treated. Blood glucose concentrations should be frequently monitored and normal glycemic values maintained. Hypotension should be avoided. ^{[5, 84]}

Optimal prehospital care is a significant determinant of outcome in the management of immersion victims worldwide. ^{[85, 86, 87]} Bystanders should call 911 immediately where this service, or similar service, is available. In developing countries, children may be transported more frequently by family members, by taxi or private vehicle, and from a greater distance. ^[33]

An individual may be rescued at any time during the process of drowning. No intervention may be necessary, or rapid rescue and resuscitation may be warranted. No two cases are entirely alike. The type of water, water temperature, quantity of water aspirated, time in the water, and individual's underlying medical condition all play a role.

The victim should be removed from the water at the earliest opportunity. Rescue breathing should be performed while the individual is still in the water, but chest compressions are inadequate because of buoyancy issues. ^[88] Victims of drowning have most likely suffered asphyxial cardiac arrest; therefore, rescue breathing as well as chest compressions are indicated as opposed to compression-only resuscitation for cardiac arrest. ^[54]

The patient should be removed from the water with attention to cervical spine precautions. If possible, the individual should be lifted out in a prone position. Theoretically, hypotension may follow lifting the individual out in an upright manner because of the relative change in pressure surrounding the body from water to air.

Bystanders and rescue workers should never assume the individual is unsalvageable unless it is patently obvious that the individual has been dead for quite a while. If they suspect injury, they should move the individual the least amount possible and begin cardiopulmonary resuscitation (CPR).

As in any rescue initiative, initial treatment should be geared toward ensuring adequacy of the airway, breathing, and circulation (ABCs). Give attention to cervical spine stabilization if the patient has facial or head injury, is unable to give an adequate history, or may have been involved in a diving accident or motor vehicle accident.

In the patient with an altered mental status, the airway should be checked for foreign material and vomitus. Debris visible in the oropharynx should be removed with a finger-sweep maneuver. The abdominal thrust (Heimlich) maneuver has not been shown to be effective in removing aspirated water; in addition, it delays the start of resuscitation and risks causing the patient to vomit and aspirate. In any event, ventilation is achieved even if fluid is present in the lungs.

Supplemental oxygen, fraction of inspired oxygen (FiO₂)100%, should be administered as soon as available. The degree of hypoxemia may be difficult to determine on clinical observation. If available, continuous noninvasive pulse oximetry is optimal. If the patient remains dyspneic on 100% oxygen or has a low oxygen saturation, use continuous positive airway pressure (CPAP) if available. If it is not available, consider early intubation, with appropriate use of positive end-expiratory pressure (PEEP).

Higher pressures may be required for ventilation because of the poor lung compliance resulting from pulmonary edema.

First responders, including emergency medical service (EMS) personnel and professional ocean lifeguards, should be well versed in providing the time-critical institution of advanced interventions, such as airway management. Refresher training in resuscitation is extremely important to strive for excellence in skill maintenance. ^{[26, 89]} With the current move toward compression-only CPR, further study needs to be performed in the specific hypoxic and potentially hypothermic milieu of drowning before this is routinely performed. ^{[83, 90]}

More traditional literature proposes that prehospital care providers should begin rewarming. Wet clothing ideally is removed before the victim is wrapped in warming blankets. More recent studies have shown that therapeutic cooling after out-of-hospital ventricular fibrillation cardiac arrest in adults may be beneficial to reduce ischemic brain injury and death. ^{[91, 92, 93]} This area needs additional vigorous clinical research to determine the most effective treatment strategy in drowning victims. ^{[84, 94, 95]}

The 1960s and 1970s saw a large body of research on drowning pathophysiology, evaluation, and management, including the development of a number of scoring systems to evaluate drowning victims. However, this work, as pointed out in a recent editorial, has not kept pace with work in cardiac and brain resuscitation and has not met the test of large randomized multicenter trials. ^[83] As such, while clearly very promising, the use of newer resuscitation methodologies, such as compression-only CPR and therapeutic hypothermia, have not been rigorously studied in drowning patients.

Patients who arrive in the emergency department in cardiopulmonary arrest after a warm-water submersion have a dismal prognosis. The benefit of resuscitative efforts should be continuously assessed. Initial management of near drowning should place emphasis on immediate resuscitation and treatment of respiratory failure. Frequent neurologic assessments should occur; the Glasgow Coma Scale is one modality that has been effectively used. Evaluate associated injuries early, particularly since cervical spine injury may complicate airway management. Initially provide all drowning victims with 100% oxygen, yet be cognizant of the goal to avoid or treat hypoxemia while minimizing hyperoxemia.

Early use of intubation and PEEP, or CPAP/bilevel positive airway pressure (BiPAP) in the awake, cooperative, and less hypoxic individual, is warranted if hypoxia or dyspnea persists despite 100% oxygen.

Endotracheal intubation and mechanical ventilation may be indicated in awake individuals who are unable to maintain adequate oxygenation on oxygen by mask or via CPAP or in whom airway protection is warranted.

Endotracheal intubation

Intubation may be required in order to provide adequate oxygenation in a patient unable to maintain a PO₂ of greater than 60-70 mm Hg (>80 mm Hg in children) on 100% oxygen by facemask. In the alert, cooperative patient, use a trial of BiPAP/CPAP, if available, to provide adequate oxygenation before intubation is performed.

Other criteria for endotracheal intubation include the following:

• Altered level of consciousness and inability to protect airway or handle secretions

• High alveolar-arterial (A-a) gradient: PaO₂ of 60-80 mm Hg or less on 15 L oxygen nonrebreathing mask

• Respiratory failure: PaCO₂ greater than 45 mm Hg

Positive end-expiratory pressure

Intubated victims of submersion injury may require PEEP with mechanical ventilation to maintain adequate oxygenation. PEEP has been shown to improve ventilation patterns in the noncompliant lung in several ways, including the following:

• Provides distending pressure to improve volume of gas at the end of exhalation (increases functional residual capacity)

• Minimizes atelectasis or alveolar collapse by maintaining pressure above which the lungs collapse (closing pressure)

• Decreases intrapulmonary shunting of blood and improves arterial oxygenation

• Increases intrathoracic pressure, which transmits the applied PEEP to transmural capillary pressure (results in minimizing interstitial lung water)

• Increases the diameter of both small and large airways to improve distribution of ventilation

Extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation (ECMO) has been shown to be beneficial in selected patients. ^[96] ECMO may be considered in the following circumstances:

• Respiratory compromise resulting from lack of response to conventional mechanical ventilation or high-frequency ventilation

• A reasonable probability of the patient recovering neurologic function

• Persistent hypothermia from cold-water drowning

Significant disorders of vascular volume are not common after drowning, although intravascular volume depletion has been attributed secondary to pulmonary edema and intracompartmental fluid shifts, regardless of the type of fluid aspirated. Clinically relevant aberrations in electrolyte concentrations are not usually found. However, hyponatremia and hypernatremia have been reported following the ingestion of large amounts of fresh or salt water. Rapid volume expansion may be indicated using isotonic crystalloid (20 mL/kg) or colloid. Inotropic support may be required using dopamine and/or dobutamine.

Most acidosis is restored after improved oxygenation and correction of volume depletion. Hypothermia may be present and exacerbate hypoxemia, acidosis, and bradycardia.

Normalization of cardiovascular function is ideal for neuroresuscitation. Vasoactive infusions may be efficacious in treating myocardial dysfunction and abnormal peripheral vascular resistance; however, the need for extended cardiovascular support is rare. Overall, treatment goals are aimed at normalization of blood pressure, maintaining organ perfusion, and facilitating gas exchange.

Nasogastric tube placement can be used for removal of swallowed water and debris. Use the orogastric route if head or facial trauma is suggested.

Bronchoscopy may be needed to remove foreign material, such as aspirated debris or vomitus plugs from the airway.

Efficacy of surfactant therapy has been reported in selected case reports. ^{[97, 98]} The routine administration of surfactant is not supported by present evidence. Use should be reserved for those with severe hypoxemic respiratory failure.

The mainstay of neuromonitoring is achieved by frequent neurologic examinations. Deterioration of brainstem function does not bode well for favorable recovery. Continuous EEG monitoring may be helpful in the assessment of subclinical seizures. No evidence supports that intracranial pressure monitoring affects the outcome in drowning victims. One could surmise the potential utility of intracranial pressure monitoring in the case of severe ARDS in order to monitor the impact of permissive hypercarbia and the effect of PEEP.

Therapeutic hypothermia

Hypothermia remains potentially beneficial and its utility has been extrapolated from adults experiencing witnessed out-of-hospital cardiac arrest ^{[94, 95]} and asphyxiated newborns. ^{[99, 100]} Aggressive resuscitation of drowning in the 1970s was notable for moderate dehydration, controlled hyperventilation, deep hypothermia (30ºC), barbiturate coma, corticosteroids, and continuous neuromuscular blockade. ^[101] Retrospective reviews determined a preponderance of survivors who remained in a persistent vegetative state ^{[102, 103]} and had increased infectious complications. ^[103] Current recommendations propose maintaining core temperature 32-34ºC for 12-72 hours. ^[54] This mode of therapy may impede the neurologic examination because of the potential need for neuromuscular blockage to blunt shivering.

Patients with severe hypothermia may appear dead because of profound bradycardia and vasoconstriction. Resuscitation should continue while aggressive attempts are made to restore normal body temperature.

Temperature management

Optimal temperature management in drowning patients is a current topic of significant research and clinical interest. Hypothermic patients with core temperatures less than 86°F who have undergone sudden, rapid immersion in cold water may experience slowing of metabolism and preferential shunting of blood to the heart, brain, and lungs, which may exert a neuroprotective effect during submersion. This is not, however, the case with most immersion victims, who have become hypothermic gradually and are at risk for ventricular fibrillation and neurologic injury.

Many authors have postulated that a primitive mammalian diving reflex may be responsible for survival after extended immersion in cold water. The mechanism for this reflex has been postulated to be reflex inhibition of the respiratory center (apnea), bradycardia, and vasoconstriction of nonessential capillary beds triggered by the sensory stimulus of cold water touching the face.

These responses preserve the circulation to the heart and brain and conserve oxygen, thereby prolonging survival. The sudden temperature drop may depress cellular metabolism significantly, limiting the harmful effects of hypoxia and metabolic acidosis

Traditional studies suggested vigorous rewarming of hypothermic patients to normothermia. In order to rewarm, a number of modalities have been used. A nasogastric tube was placed to assist in rewarming efforts and a urinary catheter was passed to assess urine output.

Core rewarming with warmed oxygen, continuous bladder lavage with fluid at 40°C, and intravenous (IV) infusion of isotonic fluids at 40°C was initiated during resuscitation. Warm peritoneal lavage has been used for core rewarming in patients with severe hypothermia. A cascade unit on the ventilator has been used to warm inspired air.

Thoracotomy, with open heart massage and warm mediastinal lavage, was used in refractory situations. The hypothermic heart is typically unresponsive to pharmacotherapy and countershock. Extracorporeal blood rewarming has been used in patients with severe hypothermia who did not respond to lavage/thoracotomy or who were in arrest.

Central venous access was suggested to be utilized cautiously in hypothermic patients, in order to avoid stimulation of the hypothermic atrium with resultant dysrhythmias.

It was suggested that resuscitation of a submersion victim not be abandoned until the patient has been warmed to a minimum of 30°C. However, newer literature, based on extensive preclinical modeling of cellular response to ischemia and reperfusion injury, as well as analyzing long-term outcome, suggests that therapeutic hypothermia can be effective in reducing ischemic brain injury. ^{[83, 94]}  Therapeutic hypothermia improves oxygen supply to ischemic brain areas, decreases cerebral metabolic demand, and decreases increased intracranial pressure.

At least 4 separate case reports of drowning victims who experienced full neurologic recovery after coma and cardiac arrest suggest that therapeutic hypothermia may confer neuroprotection. ^{[84, 104, 105]} This area needs additional vigorous clinical research to determine the most efficacious treatment strategy. In the interim, it would appear appropriate for individual jurisdiction EMS directors to meet with their local referral hospital(s) to determine current temperature management strategy.

The panel of experts at the 2002 World Congress on Drowning ^[5] made the following consensus recommendations on drowning management: "The highest priority is restoration of spontaneous circulation, subsequent to this continuous monitoring of core/and or brain (tympanic) temperatures is mandatory in the ED and intensive care unit and to the extent possible in the prehospital setting. Drowning victims with restoration of adequate spontaneous circulation who remain comatose should not be actively warmed to temperature values above 32º-34°C. If core temperature exceeds 34°C, hypothermia should be achieved as soon as possible and sustained for 12 to 24 hours..." Evidence to support the use of any neuroresuscitative pharmacologic therapy is insufficient.

Initiation of appropriate management of hypoglycemia and other electrolyte imbalances, seizures, bronchospasm and cold-induced bronchorrhea, dysrhythmias, and hypotension may be necessary in the drowning patient.

Hypoglycemia and hyperglycemia are not only associated with increased mortality and morbidity, ^[106] they are especially detrimental in patients with brain injury. The injured brain is exquisitely sensitive to aberrations in serum glucose. Normoglycemia should be the target goal.

Patient disposition depends on the history, presence of associated injuries, and degree of immersion injury. Patients can be safely discharged from the ED after 6-8 hours of observation if they meet the following criteria:

• Able to relay a good history of minor immersion injury

• No evidence of significant injury

• No change in mental status or behavior

• No evidence of bronchospasm or tachypnea/dyspnea

• No evidence of inadequate oxygenation (by ABG analysis and pulse oximetry)

Be cautious with early ED discharge in older individuals or in those with underlying medical conditions that might place them at increased risk of hypoxic injury. Victims of mild to moderately severe submersion, who only have mild symptoms that improve during observation and have no abnormalities on ABG analysis or pulse oximetry and chest radiograph, should be observed for a more prolonged period of time in the ED or observation unit.

Instruct discharged patients to return immediately if they develop dyspnea, cough, and/or fever.

Certain patients may display mild to moderately severe hypoxemia that is corrected easily with supplemental oxygen. Admit these patients to the hospital for observation. They can be discharged after resolution of hypoxemia if they have no further complications.

Between 90% and 100% of individuals who arrive in the ED with blunted mental status have been shown to survive without neurologic deficit. However, individuals who were comatose upon arrival in the ED had significantly poorer outcomes. Approximately 34% died after presentation, and an additional 10-23% survived with severe neurologic residua. ^{[107, 108]}

Admit patients who require intubation and mechanical ventilation to the ICU. Varying degrees of neurologic as well as pulmonary insults typically complicate their courses. Pulmonary hypertension may result from the release of inflammatory mediators, increasing right ventricular afterload, and decreasing left ventricular preload and pulmonary perfusion. Newer ventilatory modes, including airway pressure release ventilation and high frequency oscillatory ventilation can decrease the risk of ventilator-associated lung injury (VALI). The general ventilator management strategy strives to limit peak pressures to 25 torr, tidal volumes 6-8 mL/kg, fraction of inspired oxygen < 0.6, and optimizing PEEP to improve oxygenation. Use of permissive hypercapnia to decrease barotrauma in many patients with ARDS may not be appropriate in this setting of hypoxic ischemic CNS injury. The elevation in PCO₂ may adversely affect intracranial pressure. High levels of PEEP may be transmitted to the intracranial space and further increase intracranial pressure and additionally decrease cerebral venous return.

Meticulously monitor for evidence of ARDS; multiple organ system failure; nosocomial infection, especially pneumonia; hyperglycemia ^[109] ; and/or gastric stress ulceration. Management of ARDS due to submersion is similar to that of ARDS from other causes.

The extent of invasive monitoring needed (eg, arterial catheter, pulmonary artery catheter, central venous pressure catheter) is determined by the degree of hemodynamic or respiratory instability and the presence of renal failure.

Invasive monitoring of intracranial pressure has been suggested in both human and animal studies to be neither useful nor necessary. However, no large, well-controlled clinical trials specific to drowning have addressed intracranial pressure monitoring, electrophysiological monitoring, tissue oxygenation management, specific pharmacologic management, vigorous glucose control, and temperature management on neurologic outcome. ^{[78, 83]}

Watch for evidence of pneumonia and CNS infection. Uncommon infections may present late and unusually. Prophylactic antimicrobial therapy has not proven beneficial.

Monitor closely for bacterial and fungal infection. Evidence is insufficient to support the use of prophylactic antibiotics.

Begin aggressive rehabilitation early (as soon as tolerated) to prevent disuse injury and promote functional improvement.

Patients must be treated in a facility capable of providing appropriate, age-related intensive care if they exhibit any of the following:

• Significant hypoxia that requires intubation

• Worsening dyspnea with the potential for intubation

• Evidence of hypoxic cerebral injury

• Evidence of renal insufficiency

• Evidence of hemolysis

• Severe hypothermia requiring cardiopulmonary bypass

Patients who require care for significant cervical spine or head trauma should be managed in a facility capable of sophisticated neurologic monitoring and neurosurgical intervention. Patients with severe neurologic impairment may benefit from transfer to inpatient rehabilitation institutions.

A review of 50 cases of drowning that resulted in litigation noted that many of the deaths resulted from preventable omissions of basic safety methods, such as the following ^{[78, 110]} :

• Leaving young children unattended at water sites

• Absent or inadequate pool fencing

• Faulty pool design and poor pool maintenance

• Poor lifeguard-to-swimmer ratios

• Poorly trained lifeguards

• Lifeguard distraction and competing duties

In most instances, drowning and near drowning can be prevented with simple safety measures and common sense. Most children younger than 5 years enter a swimming pool directly adjacent to their home or one with inadequate fencing or unlatched gates or doors. Most children who drown in pools are found silently floating with no screaming or splashing having been noted, were last seen in the home, were missing at least 5 minutes, and were in the care of one or both parents at the time of the drowning. ^[25]

Children, especially toddlers, should be supervised at all times when they are around water, including a bathtub, toilet, or bucket full of water. Toilet lids should be left closed, or a child-safe fastener device utilized, when not in use. Baby bath seats do not provide additional safety for unsupervised children. Since 1983, at least 104 deaths and 126 nonfatal immersion incidents involving improperly supervised baby bath seats have occurred in the United States. ^[25]

Household buckets should be immediately emptied after use and left empty when not in use. Water-containing objects, such as water tanks and cisterns, should have childproof fastenings and solid tops. They should not have items adjacent that afford children easy access.

Adult supervision is essential in the prevention of drowning. Because lapses of supervision are inevitable, other safety precautions must be in place.

All pools should be fenced appropriately. The use of adequate fencing around swimming pools has decreased the number of immersion injuries significantly (by more than one half). The enclosure may be a wall or fence that completely surrounds a pool on all 4 sides, isolating the pool from the remainder of the property. The enclosure must be at least 4 ft tall with no more than 4 in between openings in the fence.

A house or building wall may serve as part of the enclosure only if it does not have any doors or windows through which a child may pass. Doors and gates to the pool should be self-closing and self-latching. Access to the area should be locked when not in use under adult supervision.

Pools, hot tubs, home spas, ^[111] and saunas not in use may be made safer with appropriately fitted and maintained covers and alarms, but these have not been shown to prevent drowning. Any doors and windows with access to the pool area should remain closed and locked. Toys and other objects attractive to children should not be left in the pool area.

Parents who own pools or who take their children to pools are encouraged to learn CPR. At least one parent or caretaker should remain focused on children at all times, avoiding other activities that might disturb this concentration, such as using the phone and conversing with others.

Children should wear personal flotation devices in pool areas, but these do not eliminate the need for constant supervision. Air- or foam-filled swimming tools, such as "water wings," inner tubes, and "noodles" are not substitutes for Coast Guard–approved personal flotation devices (PFDs).

Children should be taught to swim, but these lessons should not provide parents with a false sense of security. A 2009 case-controlled study concluded that participation in formal swimming lessons was associated with an 80% reduction in the risk of drowning. ^[112]

However, as an astute Florida pediatrician pointed out in an associated letter, swimming programs exist in an unregulated industry and have different objectives, methods, and goals, and these are achieved to varying degrees. Parents should be aware of the qualifications, goals, and limitations of the swimming programs in which they enroll their children. ^[113]

Infant swimming or water-adjustment programs do not prevent submersion injuries and are potentially hazardous, providing parents with a false sense of security if they perceive their infant can swim.

The presence of lifeguards at public swimming venues is also a deterrent, but it is not foolproof. Centers for Disease Control and Prevention (CDC) data suggest that 19% of drowning deaths in children occurred in public pools with certified lifeguards present. Nevertheless, trained, professional lifeguards clearly have shown a positive effect on US drowning prevention, including deterring dangerous or risky behavior, determining bathers who appear to be in distress, and determining the presence of hazardous conditions.

The ability of lifeguards to aid in drowning prevention is influenced by a number of factors. Individuals often drown quickly and are unable to call attention to themselves when in distress. As such, overcrowding of pools, lakes, parks, and beaches, as well as assignment of additional distracting duties to the lifeguards, can decrease their effectiveness. ^[114]

All individuals involved in boating activities should be able to swim, should use Coast Guard–approved PFDs when on the boat or in the water, and should avoid the use of alcohol or other recreational drugs. Boaters should be taught to anticipate wind, waves, and water temperature and to use protective suits and other insulating garments in cold weather.

Children younger than 14 years should not use personal watercrafts unsupervised by an adult. In 2002, more than 189 children younger than 14 years sustained personal watercraft injuries. ^[25] In 2000, only one third of children in this age group were wearing PFDs. As of 2009, 38 states had enacted boating safety statutes, requiring children to wear Coast Guard–approved PFDs at all times when on boats or near open water.

All children should be taught to swim with a buddy, to check for posted danger warnings, and to check the water carefully for depth and possible injurious objects before diving into water. Children should also be taught their swimming limitations and to not play dangerously in natural water areas, in pools, or on the decks surrounding pools.

All individuals should be taught not to drink alcohol or use other recreational drugs when swimming.

Individuals with underlying medical illnesses that may place them at risk when swimming, such as seizure disorders, diabetes mellitus, significant coronary artery disease, severe arthritis, and disorders of neuromuscular function, should swim under the observation of another adult who can rescue them should they get into trouble.

Individuals should not swim alone.

The American Academy of Pediatrics established guidelines for the prevention of drowning in infants, children, and adolescents in 2003, ^[115] with an update in 2010. ^[72] Recommendations may be found through the Web site: AAP Gives Updated Advice on Drowning Prevention. Prevention and consumer safety tips may be located on the Consumer Product Safety Commission site: Drowning Prevention Toolkit.

Neurosurgical, orthopedic, or trauma consultation (institution dependent) is required for patients with concomitant significant head or neck trauma. Early consultation with the intensivist or admitting physician is wise for patients who exhibit pulmonary or CNS insult in order to coordinate ongoing ICU care.

Cardiovascular, intensivist, or trauma surgical consultation may be necessary for patients who require bypass for rewarming or ECMO.

Consider neurology consultation for seizures or persistent neurologic deficit. Consider neurosurgery consultation if associated head or spine trauma, hematoma, aneurysm, or CNS abscess is present.

Consider cardiology consultation for dysrhythmias or myocardial dysfunction, pulmonology consultation for severe or persistent respiratory compromise, and infectious disease consultation for pneumonia or CNS infection.

Physical therapy, occupational therapy, and rehabilitation therapy consultation are needed to help prevent disuse injury and provide early rehabilitation.

After initial recovery, drowning patients may develop nonpulmonary infections, including brain abscesses, osteomyelitis, and soft-tissue infections with unusual fungal, amebic, and bacterial pathogens. Because the causative organisms for these infections are rarely seen in other clinical settings, a high index of suspicion must be maintained in patients after acute or subacute injury. Surgical consultation may be required because many of these infections do not respond to antimicrobial therapy alone.

Outpatient care is dictated by the nature and degree of residual functional impairment. With severe neurologic impairment, the patient may benefit from admission to a rehabilitation facility and aggressive rehabilitation. In one case report, neuropsychological testing delineated problems with memory, visuospatial performance, executive function, verbal fluency, flexibility, planning, and abstraction. Visuospatial testing, verbal learning, recall, and logical reasoning showed improvement during a 3-year follow-up period. ^[116]

The ideal independent predictor for survival is drowning time. ^[117] Poor prognostic signs for recovery include an unwitnessed event, delayed resuscitation, need for CPR at the scene, need for continued CPR in the ED, ^[118] and prolonged coma. A multitude of imaging studies (eg, CT, MRI, MR spectroscopy), ^{[119, 120]} electrophysiologic studies including brain stem auditory-evoked response (BSAER) ^[121] and somatosensory evoked potentials (SSEP), ^[122] and biomarkers have been explored to better define prognosis in drowning. At this time, there is no test or assessment that reliably predicts functional neurologic outcome. The most meaningful information with respect to prognosis is derived from an improving neurologic examination over time. ^[123]